OS OpenData products available from 1 April 2010 as an on-line service at www.ordnancesurvey.co.uk/opendata inc 1.7m postcodes
Ordnance Survey data! On data.gov.uk!
Guardian: Ordnance Survey launches free downloadable maps
Ordnance Survey Open Data licence no restriction on derived works 🙂
Ordnance Survey OS opendata maps: what does it actually include? Datablog
OpenStreetMap wiki: OS open data, what next?
Cyclestreets blog on Ordnance Survey open data and their move to OS codepoint database
#opsi statement on re-use if you add to Ordnance Survey mapping http://www.opsi.gov.uk/about/faqs-psi-regulations#rf